Frothers for the flotation of sulfidic ores

ABSTRACT

A process involving the use of a new and improved class of frothing agents in the froth flotation of ores such as the sulfide ores of copper, molybdenum, lead, nickel and zinc, as well as for separating coal fines by flotation. The class comprises the non-hydroxylated ether derivatives of dialkylene glycols such as ethylene glycol and propylene glycol. Especially good results are obtained when these frothers are employed in the treatment of complex copper-molybdenum ores.

United States Patent [191 Tveter, deceased et a1.

[ 1 Feb. 11, 1975 1 FROTIIERS FOR THE F LOTATION OF SULFIDIC ORES [75]Inventors: Elmer C. Tveter, deceased, late of Walnut Creek, Calif. byCora Belvin Judd Tveter, executrix; Guy 11. Harris, Concord, Calif.;Lowell B. Lindy, Midland, Mich.

[73] Assignee: The Dow Chemical Company,

Midland, Mich.

221 Filed: Dec. 7, 1972 211 Appl. N0.;313,1ss

[52] US. Cl. 209/166 [51] Int. Cl B03d 1/02 [58] Field of Search209/166, 167; 252/61 [56] References Cited UNITED STATES PATENTS2,065,053 12/1936 Christmann 209/166 2,302,338 11/1942 Moellen 209/166Christmanm Tueten 3,595,390 7/1971 Booth H 209/166 FOREIGN PATENTS ORAPPLICATIONS 542,966 7/1957 Canada 1,001,652 l/l957 Germany 1,004,4429/1959 Germany .1 209/166 OTHER PUBLICATIONS Chem. Abst., 1966, Vol. 65,18218d. Chem. Abst., 1969, Vol. 70, 98894n.

Primary ExaminerRobert Halper Attorney, Agent, or Firm l. R. Lockhead 6Claims, No Drawings FROTHERS FOR THE FLOTATION OF SULFIDIC ORESBACKGROUND OF THE INVENTION Heretofore, a large number of differentcompounds have been employed as frothing agents. Alcohols such as methylisobutyl carbinol and pine oil received early use in this area.Non-hydroxylated compounds have also been employed: for example, U.S.Pat. Nos. 2,591,289, 2,687,214 and 2,982,787 illustrate the use ofcompounds containing ether linkages.

It is also known that reaction products of alcohols with one or moremoles of alkylene oxide can be em ployed as frothing agents. Forexample, in U.S. Pat. No. 2,611,485, Tveter describes the use ofmonoethers of propylene glycol and of polypropylene glycols as frothers.In U.S. Pat. No. 2,950,818, Moeller teaches the use of monoethers ofethylene glycol and polyethylene gly cols as frothers.

DESCRIPTION OF THE INVENTION The invention comprises subjecting anaqueous pulp of an ore containing copper, molybdenum, lead, nickel,zinc, and the like to froth flotation in the presence of a collector anda particular organic frothing agent. The invention further comprisesremoving coal fines by the froth flotation of same utilizing thefrothers taught herein.

The organic frothing agents utilized herein correspond to the formulawherein each A is an alkylene group having 2 or 3 carbon atoms, and R ismethyl, ethyl, n-propyl, i-propyl, i-butyl or t-butyl.

Examples of frothing agents useful alone or in admixture includediethylene glycol methyl, t-butyl ether; dipropylene glycol ethyl,t-butyl ether; diethylene glycol n-propyl, t-butyl ether; dipropyleneglycol di-t-butyl ether; and dipropylene glycol i-butyl, t-butyl ether.

Frothing agents of the invention may be employed as pure compounds or,instead of using the purified compounds, reaction mixtures obtained bythe usual methods of making the compounds, or mixed fractions thereof,may also be used. The frothers ofthe invention can also be employed inconjunction with additives such as fuel oil or other frothing agents.

Frothers employed in the invention are prepared by known methods. Onesuch method is a multi-step process which involves reacting 1 or 2 molesof ethylene or propylene oxide with an alcohol having 1 to 4 carbonatoms or a mixture of such alcohols. A specific ex ample of such areaction is described in U.S. Pat. No. 2,611,485 incorporated herein byreference. The resulting hydroxy ether is capped" by reacting thehydroxyl group to form an ether, as, for example, by reacting thehydroxy ether with isobutylene using macroreticular ion exchange beadsas a catalyst (see U.S. Pat. No. 3,037,052).

In using the frothing agents, the amount employed is from about 0.001 toabout 1.00 pound per ton of ore, and preferably is from about 0.01 to0.20 pound per ton of ore. The ore is ground to a particle size suitablefor flotation. Flotation is carried out at a pulp density of from about15 to about 40 percent solids. Acidity in the pulp is controlled toprovide a pH range of from about 7 to about 12.

The frothers are employed with any of the standard collectors such asxanthates (e.g.., ethyl xanthate), dithiophosphates, phosphocresylicacids, or diphenyl thiourea. The frothers are especially suitable foruse with collectors such as those described in U.S. Pat. Nos. 3,590,997,3,590,998 and 3,590,999.

The frothing agents of the invention are applicable to sulfidic ores,primarily ores of such metals as lead, zinc, copper, molybdenum, nickel,cobalt, or antimony, which are often associated with other elements suchas silver, mercury, gold, cadmium or arsenic. The frothers findparticularly useful application in the beneficiation of complexmolybdenum-copper ores containing on the order of about 0.2 to about 1.5weight percent of copper and about 0.01 to about 0.1 weight percent ofmo lybdenum. Such ores are found in the southwestern United States(Arizona, Utah, Nevada), Western Canada (British Columbia) and inwestern South America (Peru, Chile). They may also find utility withcopper/- cobalt ores, such as are formed in southern Africa. Inaddition, they are useful in the froth flotation of coal fines.

The frothers disclosed herein are effective producers of a strong frothpossessing the physical properties required for supporting mineralparticles and permitting a relatively clean separation from gangue. Ascompared with chemically similar standard frothers such as hydroxylatedmono ethers of alkylene glycols (eg, mono and poly propylene glycol monoethers), the new agents are capable of producing an equivalent frothwith a materially smaller quantity of frothing agent, hence are markedlysuperior in specific frothing powerv In the case ofmany ores (e.g.,complex Mo-Cu sulfidic) they show a greater selectivity, producing aricher concentrate with a lower content of acid-insoluble ganguematerials. The frothers are not effective as mineral collectors butfunction solely as frothing agents. The art has long recognized,however, that it is disadvantageous for frothing agents to possess goodcollecting properties, as better selectivity is found when the twofunctions are separately performed by appropriate agents.

The following example illustrates the improved re sults obtainable byuse of the invention.

EXAMPLE 1 A series of tests was made with a coppermolybdenum oreassaying 0.68 percent copper and 0.034 percent molybdenum. The particlesize ofthe ore was minus 20 mesh. Five hundred gram samples of the orewere ground in a ball mill with 300 ml. of water and with lime inproportion of 1.5 pounds per ton of ore to prepare a pulp in which 47percent of the solids passed a 325 mesh screen. The pulp was conditionedin a flotation cell with a collector in the amount of 0.021 pound/ton ofore, and with the amount of frothing agent shown in the following table,after which the concentrate was removed in 6 minutes of frothing. Thecollector was a xanthate-derived compound corresponding generally to theformula Table I shows the analysis of the concentrate and percentagerecovery of copper and molybdenum. As a comparison, tests were carriedout using standard frothing agents. These agents were the diacetateester of ethylene glycol and also a mixture of polypropylene glycolmonomethyl ethers available commercially as Dowfroth 250 (a product ofThe Dow Chemical Com- P w)- The amounts of frother used in the testswere those passes a 200 mesh screen. The pulp was conditioned for 1minute in a flotation cell with the amount of frother shown in Table 11,after which the concentrate was removed in 3 minutes of frothing. Ineach case duplicate tests were conducted, the arithmetic average valuesfor the analysis of the concentrates and the percentages of recovery ofcopper and molybdenum being reported. As a comparison, methyl isobutylcarbinol (M.l.B.C.), which is customarily used in this process.

required to produce approximately the same volume of and Dowfroth 250were also tested as standards.

TABLE 1 Concentrate Analysis Lbs. of (Wt. 70) Frother/Ton Cu Mo RecoveryRun Frother ofOre Cu Mo 1 Diacetate ester 0.202 9.1 0.251 85.7 50.8

of ethylene glycol 2 Dowfroth 250 0.120 11.7 0.499 86.0 56.4

3 Diethylene glycol 0.090 8.1 0.335 88.4 65.5

methyl. t-butyl ether TABLE 11 Concentrate Analysis Lbs. of (Wt. 70) '7:Frother/T on Cu Mo Recovery Run Frother of Ore l1 Cu Mo 4. MlBC .07825.35 0.68 65.1 46.2

7. Dowfroth 250 .094 25.10 0.66 70.1 48.9

9. Diethylene glycol .084 20.60 0.71 83.4 71.6

methyl, t-butyl ether froth. From the results depicted in Table I, itcan be EXAMPLE 3 seen in comparison with standard frothers that use ofan exemplary frother of the invention resulted in increased copper andmolybdenum recovery even though smaller amounts of said agent wereemployed.

EXAMPLE 2 An additional series of tests was made with a coppermolybdenumore similar to that of Example 1 and assaying 0.77 percent copper and0.030 percent molybdenum. Five hundred gram samples of this ore wereground with 275 ml. of water, with lime in proportion to 0.4 pound perton of ore, and with isopropyl ethyl thionocarbamate in proportion of0.064 pound per ton of ore to prepare a pulp in which 5 percent of thesolids were retained on a 100 mesh screen and percent In another seriesof tests, an ore containing 0.33 percent of copper and 0.22 percent ofmolybdenum was subjected to a procedure similar to the above. Twelvehundred fifty gram samples of the ore were ground in a ball mill withwater to give a slurry containing per cent solids and with lime added inproportion to 4.8 pounds per ton of ore, stove oil equivalent to 0.040pound per ton of ore and a'llyl amyl xanthate equivalent to 0.012 poundper ton of ore, to prepare a pulp in which percent of the solids passeda mesh screen. The pulp was conditioned in a flotation cell with theamount of frothing agent shown in Table 111. after which the concentratewas removed in 2 minutes of frothing. At this point an amount ofpotassium amyl TABLE 111 Concentrate Analysis Lbs. of (Wt. 76) /1.Frother/Ton Cu Mo Recovery Run Frother of Ore "/0 Cu Mo 11. MlBC .0895.58 (1.421 90.25 86.21

12. Diethylene glycol .033 4.14 0.190 90.35 81.55

methyl, t-butyl ether xanthate equivalent to 0.005 pound per ton of orewas added and concentrate was removed during an additional 3 minutes offrothing. Table 111 shows the analysis of the concentrate and thepercentage of recovery screen and 60 percent of the solids passing a 200mesh screen. The pulp was conditioned for 1 minute with the frother inamount shown in the-Table following, and concentrate was removed in 5minutes of frothing. [n

of the copper and molybdenum. 5 this series, a mixture of a frothercontaining chiefly C EXAMPLE 4 and C primary alcohol (Aerofroth 71, aproduct of The procedure of Example 2 was repeated on a new ArnerlcanCyanamld Co.) was blendedwlth MlBC 1n a ore sample from the samelocation. This sample anaratio of was tested a comPansonf thls ,blendlyzed 068 percent copper and 0015 percent molybde being the customarypractice used 1n tre atlng this ore. "um Again duplicate tests were madeand Table [v 10 In each case duplicate tests were made with each froth-Shows the arithmetic average results Concentrate mg accent and theresults tabulated are the arlthmetlc analysis and metal recoveries.averages- TABLE IV Concentrate Analysis Lbs. of (Wt. Frothcr/T on Cu MoRecovery Run Frother of Ore 72 7: Cu Mo 13. MlBC 0.156 23.6 .322 55.734.0

15. Dowfroth 250 0.150 21.8 .571 69.8 85.8

16. Diethylene glycol 0.096 23.6 422 55.9 47.1 methyl, t-butyl 0.12022.7 .453 64.9 59.7 ether TABLE V Concentrate Analysis Lbs. of (Wt. 1 6)7c Frother/Ton Cu M0 Recovery Run Frothcr Of Ore Cu Mo 17. 3:1Acrol'roth .072 10.3 0.96 81.3 89.2

71/M1BC 18. Dietllylcnc glycol .072 9.4 0.88 83.4 90.1

methyl, t-butyl ether EXAMPLE 5 EXAMPLE 6 In this series of tests, anore containing 0.55 percent copper and 0.047 percent molybdenum wasground in like manner with lime equivalent to 6.0 pounds per ton, stoveoil equivalent, to 0.039 pound per ton and isopro pyl Z-methylthio ethylthionocarbamate equivalent to 0.034 pound per ton of ore to prepare apulp with 10 Additional tests were made with a different ore sample butone from the same source as Example 5. The procedure was as that ofExample 5 with the exception that the isopropyl Z-methylthio etllythionocarbamate collector was replaced as indicated in Tables VI A andV1 B following. Again, duplicate tests were averaged.

A. Using the equivalent of 0.0108 pound per ton of ethyl thionocarbamateplus 0.0108 pound per ton of ally amyl xanthate as the collector addedin the percent of the solids being retained on a mesh grinding step.

TABLE VI A Concentrate Analysis Lbs. of (Wt. /z.) "/2 Frothcrfl'on Cu MoRecovery Run Frother OfOre /6 7t Cu Mo 19. 3:1Acr0froth .240 13.42 1.3437.95 74.50

71/M1BC 20. Dielhylcne glycol .240 12.00 0.91 63.35 86.85

methyl. t-butyl other B. Using the equivalent of 0.0216 pound per ton ofisopropyl 2-ethoxyethylthionocarbamate as the collector added in thegrinding step.

fractions. The coal generally floats naturally, although occasionallyfuel oil or kerosene is added to render the coal more hydrophobic.Frothing agents such as MlBC TABLE V1 B Concentrate Analysis Lbs. of(Wt. I Frother/Ton Cu Mo Recovery Run Frother of Ore Cu Mo 21. 3:1Aerofroth 71/ .240 12.04 1.10 46.20 71.30

MlBC

22. Diethylene glycol .240 1 1.06 i 0.72 69.00 86.80

EXAMPLE 7 and pine oil are used to produce the froth. In order to In amanner similar to the procedure of the previous Examples, an orecontaining 3.83 percent total copper of which 0.74 percent was as acidsoluble copper, plus 25 pare a pulp in which 22 percent of the solidswere re- 30 tained on a 200 mesh screen. This pulp was transferred to aflotation cell and conditioned 1 minute with the amount of frother shownin the Table. Concentrate was collected during 4 minutes of frothing.For comparison tests were made with 1,1,3-triethoxybutane, known as 35Powell Acelerator (National Chemical Products), the frother customarilyused in treating this ore. The results of duplicate tests arithmeticallyaveraged are presented in the following Table.

demonstrate the ability of the frothers of the instant in vention tofroth and float coal fines, diethylene glycol methyl, t-butyl ether andMlBC were added to oxidized coal in roughly equivalent doses andflotation was carried out until all the coal fractions appeared to havefloated. 1n the case of the former, this consumed 5-10 minutes, whereaswith MlBC 20-30 minutes were required, demonstrating the superiorability of the frother of the instant invention in separating coalfines.

EXAMPLE 9 In order to illustrate the frothing ability of arepresentative group of the frothers disclosed herein, tests were madeon a copper-containing ore from Arizona, the ore assaying 1.06 percentCu. As in Example 2, 500 gram samples were ground with 300 ml. of water,with lime in proportion to 0.2 pound per ton of ore, and with iso- TABLEV11 Concentrate Analysis Lbs. of (Wt. "/t) Frother/Ton Cu Mo RecoveryRun Frothcr of Ore "/1 "/0 Cu Mo 23. 1.1.3-lricthoxy- 0.184 40.9 1.3770.0 39.7

butnnc 24. Dicthylcne glycol 0.120 37.1 1.32 76.4 45.5

methyl. t-butyl ether EXAMPLE 8 propyl ethyl thionocarbamate inproportion of 0.032

Crude coal is generally treated in a preparation plant to reduce the ashcontent resulting from continuous mining procedures. The processinvolves washing, screening and gravity separation of the coarse (+600micron) fractions and froth flotation of the fine coal pound per ton toprepare a pulp in which 7 percent of the solids were retained on a 65mesh screen. The pulp was conditioned for 2 minutes in a flotation cellwith the amount of frother shown in Table V111, after which theconcentrate was removed in 5 minutes of frothing.

5 The calculations were the same as in Example 2.

l. The method which comprises subjecting an aqueous pulp of a sulfidicore of one or more of the metals lead, zinc, copper, molybdenum, nickel,cobalt, antimony, silver, mercury, gold, cadmium and arsenic to frothflotation in the presence ofa collector and one or more organic frothingagents corresponding to the formula wherein each A is an alkylene grouphaving 2 or 3 carbon atoms, and R is methyl, ethyl, n-propyl, i-propyl.i-butyl or t-butyl.

2. The method of claim 1 wherein, in the formula, R is t-butyl.

3. The method of claim 1 wherein, in the formula, R is methyl.

4. The method of claim 1 wherein the frothing agent is diethylene glycolmethyl, t-butyl ether.

5. The method of claim 1 wherein the frothing agent is diethylene glycoldi-t-butyl ether.

6. The method of claim '1 wherein the frothing agent is diethyleneglycol ethyl, t-butyl ether.

1. THE METHOD WHICH COMPRISES SUBJECTING AN AQUEOUS PULP OF A SULFIDICORE OF ONE OR MORE OF THE METALS LEAD, ZINC, COPPER, MOLYBDENUM, NICKEL,COBALT, ANTIMONY, SILVER, MERCURY, GOLD, CADMIUM AND ARSENIC TO FROTHFLOTATION IN THE PRESENCE OF A COLLECTOR AND ONE OR MOER ORGANICFROTHING AGENTS CORRESPONDING TO THE FORMULA
 2. The method of claim 1wherein, in the formula, R is t-butyl.
 3. The method of claim 1 wherein,in the formula, R is methyl.
 4. The method of claim 1 wherein thefrothing agent is diethylene glycol methyl, t-butyl ether.
 5. The methodof claim 1 wherein the frothing agent is diethylene glycol di-t-butylether.
 6. The method of claim 1 wherein the frothing agent is diethyleneglycol ethyl, t-butyl ether.